Hi Boggiano,

Finger dexterity takes a lot to be constructed. When I first started playing I've dropped because I though I wasn't "naturally" gifted with enough dexterity to be good at playing (time, practice and effort made me realize I was very wrong). So just keep practicing everyday the root position, trying to hit all strings properly. At first might seem like an impossible task, but the only way to achieve it is practicing daily for weeks, months and years (after +1 year playing everyday I still have some troubles with barre chords, although I've made huge progress compared to what I used to do when first started).

Bottom line of all I've just said: keep practicing daily and as much as you can.

Hope it helps,

Andrés